To reinstall Universe ToonIt onto your system, head to the Universe tab on your account to find a ToonIt Legacy download option available for both Mac and Windows under the Download section.
The download will then have instructions on where to place the Legacy ToonIt files accordingly.
If you need help following the instructions contained in the files, or if this fails to fix the issue, please contact support.
Note that ToonIt is a discontinued plugin and will not be updated to work with later versions of hosts beyond 2018. If you did not have a Universe subscription prior to ToonIt's discontinuation in Jan. 2018, you unfortunately will not be able to retrieve the Universe ToonIt Legacy files.